TEMPORAL ARTERITIS: DECISION MAKING MODELS AND STUDIES is a clinical research project directed at a basic question in quantitative medical decision making. The central scientific question is: Can a model of prognosis be developed for diverse chronic diseases, that can incorporate data on survival and the quality of a patient's life? In this project the Markov process, a time-dependent probability model that depends on clinical states of health, is adapted to the rheumatologic problem of the natural history of suspected temporal arteritis in polymyalgia rheumatica. The immediate objective of the research is an analysis of the natural history, diagnostic and management options in polymyalgia rheumatica; the long-term objective is the establishment of the Markov model as a general-purpose model of medical prognosis. Both conventional and novel methods of clinical research will be employed in this study. Data for the Markov model will be collected by literature review, by retrospective chart review on an identified cohort of patients with polymyalgia rheumatica, by interviewing new patients with polymyalgia rheumatica/temporal arteritis, and by following all existing patients with the disease for three years. Attitudes of individual patients toward longevity and quality of life will be assessed using techniques of utility analysis. The information gained by these diverse means will be integrated into a decision analytic model of the diagnostic and treatment decisions in polymyalgia rheumatica. This model will incorporate aspects of standard decision analysis, as well as newer methodologies such as outcome modeling and probabilistic sensitivity analysis. The Markov process will be developed as the outcome model in the analysis. This project should lead to recommendations concerning the clinical management of suspected temporal arteritis, as well as information about the suitability of Markov modeling in chronic diseases.